How Much Penicillin to Give a Cat? The Right Dosage You Need to Know


What is Penicillin and how does it work?

Penicillin is a group of antibiotics commonly used to treat bacterial infections. Most commonly, they are used to treat infections caused by staphylococci or streptococci. Penicillin interrupts the bacteria's cell walls and prevents them from producing a functional cell wall as soon as they breed. Various strains of bacteria have developed resistance to penicillin over time but it is still a highly efficient drug to a lot of infections.

Penicillin is commonly administered through a subcutaneous or intramuscular injection. Sometimes, depending on the type of infection your cat has, your vet may administer penicillin directly into a vein. To treat an ongoing infection, many veterinarians prescribe an oral pill the owner may administer.


There's essentially an extensive array of penicillin in the market, including:

  • Natural penicillin - widely recommended for meningitis, strep throat or other oral infections.
  • Penicillinase-resistant penicillin - commonly prescribed for staph infections and deals with thinner spectrum.
  • Aminopenicillin - effective towards the obliteration of gram-negative bacteria.
    Extended-spectrum penicillin - works the same with aminopenicillin but have a wider spectrum.

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Can't decide whether or not your feline friend may need an antibiotic? Consult your veterinarian in order to ensure your cat is as happy and healthy as can be.


Cats are tough creatures and surely know how to hide their pain, but some noticeable signs tell you if they may be in poor health. Viral infections, bacterial infections, or fungal infections can all negatively impact the health of your cat.

If you notice your feline is lethargic or has fever or diarrhea, he/she may have contracted a bacterial infection. This should be treated with an antibiotic such as penicillin. When prescribed by a veterinarian, you can give administer penicillin to your cat. It's important to know the correct dosage and directions when administering the medication.

When to use Penicillin for your cat?

cat looking at penicilin

Penicillin should only be used for your cat when prescribed by a certified veterinarian. Penicillin is a commonly prescribed drug and has several health benefits in treating illness and infection.

Penicillin is often prescribed if your cat has or is prone to urinary tract infections, soft tissue infections, ear infections, respiratory infections, and or skin infections/lesions.

It is not uncommon for veterinarians to prescribe penicillin as a precautionary measure when they have yet to accurately determine the type of infection or are waiting on lab results.

Some studies show that penicillin can be harmful to a cat if he/she is pregnant. Consult with your veterinarian before administering penicillin to your cat.



There are numerous factors veterinarians consider when determining dosages such as height, weight, age and the severity and type of infection being treated.

A common technique many veterinarians use and you can use to ensure your cat is being administered the right dosage

  • For instance, if your cat is 9.9 pounds, you should give him 1/2 - 1 tablet size of penicillin.
  • Those cats with a weight of more than 4.96, a 1/2 tablet size is needed.
  • Ask your vet about the right dosage to avoid potential risks.

Are There Possible Side Effects?

Yes. Among the side effects, you need to watch out for include:

  • Itchiness
  • Vomiting
  • Diarrhea
  • Facial swelling
  • Difficulty breathing
  • Loss of appetite
  • Joint pains
  • Hives and another form of skin rashes
  • Liver or kidney damage

Gastrointestinal upset and anaphylaxis (a severe type of allergic reaction) are the most serious side effects. To reduce the side effects, administer the drug during mealtimes.


If your veterinarian recommends you as the owner administer penicillin, be sure to receive proper training and advice from the vet in order to safely and properly administer the medication

Administering tablets:

  • Mix with food and serve it to your cat.
  • Hide the pills in semi-wet or wet food areas in which liquid penicillin blends in dry treats.
  • Utilize "pill pockets", available at several pet stores

Administering liquid penicillin:

  • Mix with wet food and then serve.
  • The food must be way beyond the medicine proportion-size so your cat would be lured to eat it.

Follow the medicinal schedule provided by your veterinarian. Make sure your feline gets his/her medicine on a regular and consistent basis. Even if your cat no longer shows any symptoms of illness, finish out the prescription provided by your veterinarian in order to ensure the infection is completely gone.

Giving penicillin to your cat needs confidence, skill, and patience. If you think you're not capable of doing the job properly, don't be afraid to ask help from your veterinary care team.

To Wrap It Up

Penicillin is a useful drug within animal healthcare and can treat a wide variety of illnesses. Only administer penicillin to your pet if prescribed by a veterinarian and you feel confident in doing so. Follow the dosage and timing when administering penicillin to your cat. Don't be afraid to ask your veterinarian if you have any questions regarding penicillin or your cat's overall health.

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